Objective. To evaluate the influence of the use of face masks on resting heartrate (HR) and physical activity in adults aged 18 to 60 years, in the city of Lima, during the COVID-19 pandemic in 2020. Methods. An experimental, analytical, prospective and cross-sectional study was carried out. For data collection, a virtual survey was carried out via Google Forms, with a series of questions and indications for the correct measurement of HR in different situations: at rest, immediately after activity and 5 min after physical activity with and without the use of masks (KN95, fabric, surgical and N95). For the present study, the possible causes of increased HR were analyzed, so 60 asymptomatic adults, 40 women and 20 men, in the age range of 18 to 60 years, were selected. Results. It was found that the difference in mean HR with and without mask use immediatelyafter physical activity increase...